The invention relates to a limiting device for the steering angle input in an electrical steering system.
In steering systems without mechanical connection to the steering gear (steer-by-wire), a mechanical feedback is missing between steering angle input by the driver via the steering wheel and the actually executed steering angle on the wheel. The steering gear can thus also move toward the limit stops, without being noticed on the steering angle input side on the steering wheel. As a result, infinitely great steering angle wishes can thus be generated, for example a free spinning of the steering wheel, without the steering gear being able to implement these steering angle wishes. It may even result in damage to the steering system. Further, steering systems of this type have also no steering wheel blockages whatsoever, a so-called steering lock, as is expected from current steering systems for motor vehicles.
US 2003/0146038 A1 discloses a steering system for steering wheels of a motor vehicle. The steering system includes a steering wheel in order to command steering wishes to the steered wheels, and a steering shaft which is mechanically coupled to the steering wheel. A housing is disposed on the steering column. A slider element is axially slideable in the housing, and a groove is formed in the steering shaft to receive the slider element. The groove includes two end walls to limit the rotational movement of the steering wheel. Thus, a firmly defined movement or rotation range of the steering wheel is defined. A variation of the stop position is, however, not provided.
US 2004/0011585 A1 discloses a steer-by-wire steering system having a mechanical feedback device that transmits a steering feel to the driver and which has a positive stop function. For the stop function, various possibilities of rigid steering stops are disclosed, mostly by blocking gears or winding and unwinding of coil springs. A variation of the stop position is not provided.
Since in electric steering systems without mechanical connection from steering wheel to steering gear, the steering ratios on the wheel can also be changed fluidly and in fact are changed, the respective steering stops must track or be adjusted in a fully variable manner.
DE 603 03 081 T2A discloses a generic limiting device for the steering angle input in an electric steering system.